1. Field of the Invention
This invention relates generally to apparatus for moving an object, and in particular relates to apparatus generally referred to in the art as sheet feeders for feeding individual sheets of cut paper into, and into and out of, printers, typewriters and other paper handling apparatus such as duplicators, etc.
2. Description of the Prior Art
The prior art is replete with many different apparatus for moving various objects and many types of sheet feeders are also known to the prior art for feeding individual sheets of cut paper as distinguished from continuous rolls of paper.
Generally, such prior art sheet feeders utilize a drive roller in contact with the top sheet of a stack of cut sheets of paper to feed the sheets of paper individually into a printer, typewriter or the like. The contact between the drive roller and the individual sheets of cut paper is usually effected by either urging the stack of paper into contact with the drive roller or by maintaining continuous contact between the drive roller and the stack of paper and by intermittently rotating the drive roller when paper feed is desired. The coefficient of friction of the drive roller, that is the surface texture, is varied to enable movement of different weight paper.
The prior art sheet feeders also typically move the drive roller into contact with the paper through the use of solenoids which move the shaft upon which the drive roller is rotatably mounted. Upon the drive roller contacting the paper, a motor typically connected to the drive roller shaft through a belt is energized to rotate the roller and move the engaged paper.
Movement of paper sheets by such prior art sheet feeders thus necessitates use of a motor, or motors, to rotate the drive rollers, belts to connect the motors to shafts or components to be driven, solenoids to place drive rollers in contact with the paper and all of the necessary bearings, journals, etc. to permit proper functioning of the various parts. The construction and maintenance of such prior art sheet feeders is accordingly costly, their reliability is hampered by the relative movement of so many components, and the trouble free service life of such feeders is limited by the need to replace components subject to wear. Also, the use of solenoids generally requires undesirable excess, electrical power to be provided to the prior art sheet feeders. Most importantly, use of such solenoids produces electromagnetic interference with other electronic circuitry in the vicinity of the solenoids and also with the circuits required to control the sheet feeder itself.
Moreover, the typical prior art sheet feeder is not capable of handling paper and envelopes of varying widths since the bottom corner triangular stops generally used to assure single sheet feeding (or other equivalent means presently known) are not laterally adjustable. Consequently, different paper trays must be installed each time a user wishes to change paper sizes; this is particularly undesirable, inefficient and costly.
Furthermore, many prior art sheet feeders do not incorporate any bail actuator assembly and, therefore, for fully automatic feeding, they must be used in conjunction with printers having such a feature, thus limiting the range of use of such sheet feeders to compatible printers or typewriters. Moreover, existing bail actuating devices even if included in prior art sheet feeders, also utilize solenoids which need to be continuously energized whenever the bail is at any position other than resting against the platen. This is also undesirable, inefficient and costly.